[Q] Save the TA partition on Xperia Z3 topic

Hello everybody !
I wanted to root my new Sony Xperia Z3, but in order to avoid some problems, I read that is important to save his TA partition. So, to root my phone, I have to unlock bootloader, and before unlock my bootloader, I have to save my TA partition. But, the stupid problems is : to save my TA partition, I must have a rooted phone !! It's totally stupid ??!! I whant to root my phone, but to root my phone I need that my phone is rooted ???? WTF ?!

So I have some questions :

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@gregbradley
- Save his TA partition is an obligation ?
- Easy way to root Xperia Z3 ?

Thanks for your future answer :D !